U.S. Pat. No. 6,009,000 issued Dec. 28, 1999 to Kasemsan Siri, referred to as Siri000, entitled Shared-Bus Current Sharing Parallel Connected Current-Mode DC to DC Converters, here incorporated by reference, teaches a power system consisting of parallel connected current-mode power converters combined with a voltage error signal on a shared-bus used in common for controlling all of the power stages for improved consistency, reliability, and performance in both transient and steady states. Near uniform current sharing is achievable without sacrificing the voltage regulation performance. The improved system offers faster settling time under step loads, consistent small signal characteristics, and large signal responses regardless of mismatches of component values such as reference voltages, and reduced output impedance variations in magnitude and phase even during various modes of operation.
Referring to FIGS. 3 and 5 of prior art Siri000, the current error amplifier 91a or 91b can be used for current limiting operation, including a current reference IREF 92a (or 92b), a current sensing signal ISense using a current sensing resistor 79, and a pull down diode 90a (or 90b) for pulling down (or pushing up) a voltage control signal VC. The voltage error amplifier 84a (or 84b) can be used for voltage regulation using the output voltage VLoad to a load and using a reference voltage VREF 85a (or 85b) and a pull down diode 86a (or a push up diode 86b) for pulling down (or pushing up) the voltage control signal VC. Current limiting and voltage regulation are well known functions that have been integrated into multiple converter power systems.
U.S. Pat. No. 7,151,362 issued Dec. 19, 2006 to Kasemsan Siri, referred to as Siri362, entitled Uniform Converter Output Voltage Distribution Power System, here incorporated by reference, teaches a uniform converter output voltage distribution power system evenly controls the individual output voltages of DC-to-DC parallel-input series-output connected converters using a uniform output voltage distribution controller including a generator for generating respective error signals from the converter output voltages using a common distribution reference signal for providing respective converter control signals connected to the converters through respective shared-bus controls for evenly distributing the power delivered by the converters that are shared-bus current-mode converters for preferably providing high output voltages. Employing a common regulation control signal, the controller can also provide system output voltage regulation, system input current limiting, proportional-voltage control, relaxed voltage uniformity, and fault-tolerant power control.
Referring to prior art FIG. 1 herein, as an example of the power system shown in FIG. 1 of Siri362, a parallel-input connected serial-output connected converter power system has an input voltage Vin1 that is fed through line impedance ZinSI for providing input currents Ii1, Ii2, and Ii3 respectively to first, second, and third DC to DC power converters having three voltage outputs Vo1, Vo2, and Vo3 that are serially connected together providing three serial-output voltages V1, V2, and V3 where the first serial-output voltage V1 serves as the output voltage V0 that is applied across a bus stabilizer BS and a load capacitor C. A power-return node of the system output voltage can be designated as an ISEN signal, which is the voltage sensed across a current-sense resistor being inserted between the load ground and the power-return node of the power system output voltage. The power system include three diodes D1, D2, and D3 for respectively connecting three voltage controls VC1, VC2, and VC3 to share bus inputs SB1, SB2, and SB3 of the first, second, and third DC to DC power converters for providing distributed power sharing among the first, second, and third DC to DC power converters.
The parallel-input connected serial-output connected converter power system of Siri362 uses a generalized uniform output voltage distribution controller shown in FIGS. 1 and 2A of Siri362. The uniform output voltage distribution controller includes a uniform voltage distribution controller 74 providing N named error voltages Vd1, Vd2, through VdN for any N number of converters. N summers 76, 78, through 80 respectively sum a control voltage VC with the N named error voltages Vd1, Vd2, through VdN for providing N respective voltage control signals Vc1, Vc2, through VcN. The control voltages Vc1, Vc2, through VcN or particularly Vc3 for N=3, are connected through respective diodes and to share bus input SB1, SB2, and SB3 of the three DC to DC power converters #1, #2, and #3. The use of a uniform output voltage distribution controller for controlling respective converters to achieve a uniform output voltage distribution is known.
Related U.S. patent application Ser. No. 11/713,826, filed Feb. 21, 2007, publication number 20080197825, referred to as Siri825, published Aug. 21, 2008, entitled “Uniform Converter Input Voltage Distribution Power System”, being prior art to the present application, teaches a uniform converter input voltage distribution power system evenly controls the individual input voltages of DC-to-DC series-input parallel-output connected converters using a uniform input voltage distribution controller including a generator for generating respective error signals from the converter input voltages using a common distribution reference signal for providing respective converter control signals connected to the converters through respective shared-bus controls for evenly distributing the power delivered by the converters that are shared-bus current-mode converters for preferably providing a low output voltage. Employing a common regulation control signal, the controller can also provide system output voltage regulation, system input current limiting, proportional-voltage control, relaxed voltage uniformity, and fault-tolerant power control.
Referring to prior art FIG. 2 herein, as an example of the power system shown in FIG. 1 of Siri825, a serial-input connected parallel-output converter power system including three DC to DC converters having a parallel connected output provide an output voltage V0 driving a bus stabilizer BS, and output capacitance C. An input voltage Vin1 is communicated through line impedance ZinP1. The input voltage is realized by serially connecting serial-input voltages V1, V2, and V3 respectively with respect to ground using series-connected input capacitors Cin1, Cin2, Cin3 having respective converter input voltages of Vi1, Vi2, and Vi3. The converter input voltages are fed to the three converters #1, #2, and #3, respectively. Three voltage control signals VC1, VC2, and VC3 are respectively fed through resistors R1, R2, and R3 through three respective optocouplers that are respectively coupled to share bus inputs SB1, SB2, and SB3 of the three converters #1, #2, and #3, for controlling the power output of the converters #1, #2, and #3. The optocouplers have their optoinput circuits being biased in common by a bias voltage VCC with respect to ground GND whereas their two-terminal optocontrolled isolated outputs being connected to their respective share bus inputs and their respective converter-input power-returns. This converter power system enables uniform power distribution between the converters #1, #2, and #3 as they are respectively controlled by the voltage control signals VC1, VC2, and VC3.
The prior art teaches voltage regulation, current limiting, and share bus input control of a bank of converters for uniform power distribution between the converters in a uniform power distribution system. These systems teach expanding the number of converters within the same bank to provide sufficient power to a load. Contrary to the teachings of the prior art, these uniform-power distribution power systems could be replicated to provide an increased amount of power to a load as desired through use of two or more banks of converters, each of which having its own dedicated input power source for an independently-sourced converter power system or sharing a common input power source for a single-source converter power system. Each of the banks of converters could be considered a power channel.
As such, a hypothecated nonprior art channelized power system could have a plurality of converter channels with power distribution perfected, according to the teachings of the prior art, within each of the channels. Such a channelized power system would lack active current-sharing among the existing channel output currents, leading to far from uniform current-sharing among nearly identical paralleled channels of the series-connected converters with their channel outputs being shared by a common load. Such a hypothecated nonprior art channelized power system would have unreliable output voltage regulation, during both in steady state and transient conditions, because there exist inherent control conflicts among the individual output voltage regulation circuits individually distributed within each the hypothecated channels of the series-connected converters. Such a hypothecated nonprior art channelized power system would have nonuniform power flows among multiple channels of series connected converters leading to unequal utilization, consequently degrading the system reliability. Such a hypothecated nonprior art channelized power system would have undesirable interactions among series connected converters, because of a natural tendency toward nonuniform distribution of series-connected converter voltages, leading to complicated stability design and analysis due to different modes of operation among series connected converters, each of which is not properly controlled under dedicated voltage regulation control. These and other disadvantages are solved or reduced by using the invention.